NO753134L

NO753134L -

Info

Publication number: NO753134L
Application number: NO753134A
Authority: NO
Inventors: I M Dow
Original assignee: Sec Dep For The Env In H B M S
Priority date: 1974-09-17
Filing date: 1975-09-15
Publication date: 1976-03-18
Also published as: US3996555A; ES440956A1; NL7510950A; BE833474A; AU497524B2; FR2285267B3; GB1505081A; DE2541480A1; FR2285267A1; JPS5160886A; SE7510335L; DK413275A; AU8486775A

Description

Anordning for identifisering av et kjbretbyDevice for identifying a kjbretby

på en veibane.on a road.

Foreliggende oppfinnelse angår et system for identifisering av et kjoretoy som kjbrer langs en forutbestemt veibane. The present invention relates to a system for identifying a vehicle that drives along a predetermined roadway.

I britisk patent nr. 1.209.482 er beskrevet et system for identifikasjon av kjbretbyer som har betegnelsen MAVIS i(Modulated Automatic Vehicle Identification System) hvorved et kjoretoy er utstyrt med en isolert elektrisk slbyfe som periodisk blir kortsluttet, idet kjbretbyet når det er i nærheten av en induktiv slbyfe i veibanen forårsaker en impedansforandring i veibanens slbyfe, mens kortslutningsmbnstret utgjor identifikasjonssignal for kjbretbyet. Dette systemet kan komme i tillegg til kjbretby-détektorer med fast frekvens, som for tiden har bred anvendelse. British patent no. 1,209,482 describes a system for the identification of towpaths which has the designation MAVIS i (Modulated Automatic Vehicle Identification System), whereby a vehicle is equipped with an isolated electric slbyfe which is periodically short-circuited, as the towpath when it is nearby of an inductive slbyfe in the roadway causes an impedance change in the roadway's slebyfe, while the short-circuit barrier forms an identification signal for the roadway. This system can be added to kjbretby detectors with fixed frequency, which are currently widely used.

Dette systemet krever imidlertid at kjbretbyets slbyfe bare kanHowever, this system requires that the city's slbyfe only can

ha en torn, som må være så stor som kjbretbyets dimensjoner tillater, og må være montert så l*avt som mulig på dette, hvilket gjor det vanskelig å tilpasse den. Den relative posisjon av kjbretbyets slbyfe og veibanens slbyfe er kritisk, signal/stby forholdet på identifikasjonssignalet er lavt, og bryteren har kort levetid hvis ikke apparatet da er operativt bare i nærheten av en veibaneslbyfe. have a thorn, which must be as large as the kjbretby's dimensions allow, and must be mounted as low as possible on this, which makes it difficult to adapt it. The relative position of the bridge's slbyfe and the roadway's slbyfe is critical, the signal/stby ratio of the identification signal is low, and the switch has a short lifetime if the device is then only operational in the vicinity of a roadway slbyfe.

Foreliggende oppfinnelse frembringer et forbedret system for identifikasjon av kjbretbyer, som hvis nbdvendig kan være kompatibelt med en kjbretbydetektor med fast frekvens. The present invention provides an improved system for the identification of bridge towns, which, if necessary, can be compatible with a bridge town detector with a fixed frequency.

I henhold til oppfinnelsen er et kjoretoy utstyrt med en isolert flertbrns slbyfe, anordnet på kjbretbyet slik at den sammen med en veibaneslbyfe danner en transformator når nevnte slbyfer er nær hverandre. Videre er det utstyrt med en anordning for avstemning av kjbretbyslbyfen slik at der fremkommer en sloyfekrets på kjbretbyet som har resonans ved en fbrste frekvens, samt en anordning forramodulasjon av nevnte sloyfekrets på kjbretbyet med en andre frekvens. I bruk kan da et signal modulert med nevnte andre frekvens overfores ved induksjon fra kjbretbyets slbyfe til nevnte veibaneslbyfe og tjene til identifisering av nevnte kjoretoy. According to the invention, a vehicle is equipped with an insulated multi-burner slbyfe, arranged on the bridge so that it together with a roadway slbyfe forms a transformer when said slbyfe are close to each other. Furthermore, it is equipped with a device for tuning the kjbretbyslbyfen so that there appears a loop circuit on the kjbretby which has resonance at a first frequency, as well as a device for pre-modulation of said loop circuit on the kjbretby with a second frequency. In use, a signal modulated with said second frequency can then be transmitted by induction from the roadway slbyfe to said roadway slbyfe and serve to identify said vehicle.

Nevnte anordning for modulasjon av slbyfekretsen på kjbretbyet kan utfores slik at den periodisk kortslutter en del av eller hele denne sloyfekrets, og denne kortslutning kan utfores ved en faststoffvender. Said device for modulating the sloyfe circuit on the cable can be designed so that it periodically short-circuits part or all of this sloyfe circuit, and this short circuit can be performed by a solid-state inverter.

Nevnte fbrste frekvens er fortrinnsvis 50-150 kHz, mens nevnte andre frekvens er fortrinnsvis 300-3000 Hz. Said first frequency is preferably 50-150 kHz, while said second frequency is preferably 300-3000 Hz.

Kjbretbyets slbyfeMtan bestå av en trådvikling, fortrinnsvis med 15-25 torn, og slbyfen er fortrinnsvis flat og hovedsaklig parallell med kjbrebanens overflate. En passende stbrrelse for denne slbyfen på kjbretbyet er ca. 300 mm i kvadrat. Alternativt kan kjbretbyets slbyfe være en ferrittantenne. Slbyfen er fortrinnsvis skjermet på den siden som vender mot kjbretbyets chassis. Kjbretby's slbyfeMtan consists of a winding of wire, preferably with 15-25 thorns, and the slbyfe is preferably flat and mainly parallel to the surface of the kjbret track. A suitable stbrrel for this slbyf in the kjbretbyet is approx. 300 mm square. Alternatively, the kjbretbyet's slbyfe can be a ferrite antenna. The slbyfen is preferably shielded on the side facing the kjbretby's chassis.

I henhold til et annet trekk ved oppfinnelsen omfatter systemet for identifisering av kjbretbyer en veibaneslbyfe på eller i veidekket, en anordning for avstemning av denne slbyfen, en anordning for tilfbrsel av energi til veibaneslbyfen vedeen fbrste frekvens i det minste i nærheten av resonansfrekvensen for den avstemte veibaneslbyfen, samt en identifiseringskrets for kjbretbyer bestående av én anordning for demodulasjon og en anordning for frekvensdeteksjon arrangert slik at de detekterer i veibaneslbyfen ethvert signal ved nevnte fbrste frekvens modulert med nevnte andre frekvens, idet nevnte andre frekvens produseres som tidligere beskrevet av et kjoretoy, for identifisering av dette, og idet nevnte fbrste frekvens er felles for slbyfene på kjbretbyet og i veibanen, fortrinnsvis i området 50-150 kHz. veibaneslbyfen har fortrinnsvis 1-3 torn. According to another feature of the invention, the system for the identification of road signs comprises a roadway signal on or in the road surface, a device for tuning this signal, a device for supplying energy to the roadsign at a first frequency at least close to the resonant frequency of the tuned the roadway slbyfen, as well as an identification circuit for road cities consisting of one device for demodulation and a device for frequency detection arranged so that they detect in the roadway slbyfen any signal at said first frequency modulated with said second frequency, said second frequency being produced as previously described by a vehicle, for identification of this, and since the mentioned first frequency is common to the slbyfs on the kjbretby and in the roadway, preferably in the range 50-150 kHz. The road slbyfen preferably has 1-3 thorns.

Det er å foretrekke at frekvensdetektoren har et visst antall tonedekodere, slik at signaler modulert med forskjellige verdier for andre frekvens kan detekteres individuelt, og slik at forskjellige klasser av kjbretbyer på denne måten kan identifiseres. It is preferable that the frequency detector has a certain number of tone decoders, so that signals modulated with different values for other frequencies can be detected individually, and so that different classes of digital cities can in this way be identified.

Resonansfrekvensen i den avstemte veibaneslbyfen kan avvike fraThe resonant frequency in the tuned roadway slbyfe may deviate from

den fbrste frekvens opptil ca. 5 %, og nevnte anordning for kjbretbyidentifisering kan ha en anordning for fasediskriminering koplet til veibaneslbyfen og arrangert slik at den avgir et utgangssignal hvorved et kjoretoy kan detekteres uten at dette er utstyrt med en slbyfe, gjennom en faseforandring i et signal ved nevnte fbrste frekvens som forekommer i veibaneslbyfen, når nenvte kjoretoy er i nærheten. the first frequency up to approx. 5%, and said device for vehicle identification can have a device for phase discrimination connected to the roadway slbyfe and arranged so that it emits an output signal whereby a vehicle can be detected without this being equipped with a slbyfe, through a phase change in a signal at said first frequency which occurs in the road lane, when the said vehicle is nearby.

I henhold til nok et trekk ved foreliggende oppfinnelse omfatterAccording to yet another feature of the present invention comprises

et system for identifisering av et kjoretoy en veibaneslbyfe på eller i veibanen, en anordning for avstemning av denne veibaneslbyfen, og en anordning for tilfbrsel av energi til veibaneslbyfen ved en fbrste frekvens i det minste nær opptil resonansfrekvensen for den av avstemte veibaneslbyfen. Videre omfatter systemet en isolert flertbrns slbyfe montert på minst ett kjoretoy som skal identifiseres når det kjbrer på den veibane som er utstyrt med nevnte veibaneslbyfe, på en slik måte at den danner en transformator med nevnte veibaneslbyfe når nevnte to slbyfer er nær hverandre, en anordning for avstemning av nevnte kjbretbyslbyfe slik at den utgjor en resonanskrets med resonans i det vesentlige ved nevnte fbrste frekvens, en anordning for modulaspn av kjbretbyets sloyfekrets med en andre frekvens, og en krets for kjbretbyidentifisering som omfatter- en anordning for demodulasjon og en anordning for frekvensdetekspn arrangert slik at de detekterer ethvert signal i veibaneslbyfen ved nevnte fbrste frekvens som er modulert med nevnte andre frekvens. a system for identifying a vehicle a roadway signal on or in the roadway, a device for tuning this roadway signal, and a device for supplying energy to the roadway signal at a first frequency at least close to the resonant frequency of the tuned roadway signal. Furthermore, the system comprises an isolated multi-burner slbyfe mounted on at least one vehicle which is to be identified when it is driving on the roadway equipped with said roadway slbyfe, in such a way that it forms a transformer with said roadway slbyfe when said two slbyfe are close to each other, a device for the tuning of said kybretbyslbyfe so that it forms a resonant circuit with resonance essentially at said first frequency, a device for modulating the kybretby's loop circuit with a second frequency, and a circuit for kybretby identification comprising - a device for demodulation and a device for frequency detection arranged so that they detect any signal in the roadway signal at said first frequency which is modulated with said second frequency.

Tonedekodere for frekvensdeteksjon, samt en anordning for fasediskriminering, kan være anordnet i forbindelse med veibaneslbyf en som nevnt. Tone decoders for frequency detection, as well as a device for phase discrimination, can be arranged in connection with road traffic control as mentioned.

Oppfinnelsen vil nu bli beskrevet, bare ved hjelp av eksempel,The invention will now be described, by way of example only,

med henvisning til vedlagte tegninger, hvori:with reference to the attached drawings, in which:

Fig. 1 viser skjematisk et forbedret system for identifisering av kjbretbyer i henhold til foreliggende oppfinnelse, Fig. 2 er en grafisk fremstilling av det mottatte identifiserings-signal som funksjon av den relative posisjon av kjbretbyets slbyfe og veibanens slbyfe, Fig. 3 viser i mere detalj den apparatur som er montert på det kjoretoy som skal identifiseres, og Fig. 4 viser skjematisk et forbedret system for identifisering av kjbretbyer som er kompatibelt med en konvensjonell detektor med fast frekvens. Fig. 1 schematically shows an improved system for identifying bridge towns according to the present invention, Fig. 2 is a graphical representation of the received identification signal as a function of the relative position of the bridge town's slbyfe and the roadway's slbyfe, Fig. 3 shows in more detail the apparatus mounted on the vehicle to be identified, and Fig. 4 schematically shows an improved system for the identification of cyber cities which is compatible with a conventional detector with a fixed frequency.

På fig. 1 er vist en veibaneslbyfe 10, vanligvis rektangulær,In fig. 1 is shown a roadway slbyfe 10, usually rectangular,

som er anbrakt på eller i veidekket, idet den typisk er utfort ved å"vikle en, to eller tre torn med tråd og strekker seg 1800 mm i kjøreretningen. which is placed on or in the road surface, as it is typically extended by wrapping one, two or three thorns with wire and extends 1800 mm in the direction of travel.

Veibaneslbyfen er koplet til en variabel kondensator 12, og forsynes med elektrisk energi i form av et signal fra en krystallstyrt oscillator 16 via et drivertrinn 17 og en transformator 14, idet kondensator 12 kan justeres slik at denne sloyfekrets i veibanen kan svinge ved en fbrste frekvens f^. The roadway slbyfen is connected to a variable capacitor 12, and is supplied with electrical energy in the form of a signal from a crystal-controlled oscillator 16 via a driver stage 17 and a transformer 14, the capacitor 12 being adjustable so that this winding circuit in the roadway can oscillate at a first frequency f^.

Utstyret på kjbretbyet som skal identifiseres er vist innenfor den stiplede ramme 18. Det kan bestå av en kjoretoyslbyfe 20 med mange torn, f.eks. 20 torn med tråd utformet som et rektangel på 300 mm x 300 mm, stbpt i epoksy harpiks og tilpasset kjbretbyets. underside. En variabel kondensator 22 er koplet i serie med kjbretbyslbyfen og justert slik at denne slbyfekretsen har resonans ved frekvens f^. Parallelt med kondensator 22 er der en bryter 24 som tjener til å kortslutte kondensator 22 periodisk med en frekvens t^ i som betegnes modulasjonsfrekvensen. The equipment on the kjbretbyet to be identified is shown within the dashed frame 18. It may consist of a kjortoyslbyfe 20 with many thorns, e.g. 20 thorn with wire designed as a rectangle of 300 mm x 300 mm, stbpt in epoxy resin and adapted to kjbretbyets. underside. A variable capacitor 22 is connected in series with the kjbretbyslbyfen and adjusted so that this slbyfe circuit resonates at frequency f^. Parallel to capacitor 22 there is a switch 24 which serves to short-circuit capacitor 22 periodically with a frequency t^ i which is designated the modulation frequency.

Den kretsen som identifiserer kjbretbyet er vist innen den stiplede rammen 26. Fra transformator 14 går signalet forst via et RF filter 27 og inn i en demodulator 28. Derfra går et eventuelt modulasjonssignal via et båndpassfilter 29, en for-sterker 30, en tonedekoder 32A for deteksjon; av modulasjonssignalet, hvilket via viklingen 34A får releet 36A til å gi indikasjon av nevnte modulasjon, når den er oppfanget av veibaneslbyfen fordi et kjoretoy er i nærheten av denne. Dette skyldes at slbyfene 10 og 20 da utgjor en fransformator, riktignok med lav virknings-grad, all den stund dens kjerne alltid vil i det minste delvis ikke være annet enn luft. The circuit that identifies the city is shown within the dashed frame 26. From transformer 14, the signal first goes via an RF filter 27 and into a demodulator 28. From there, any modulation signal goes via a bandpass filter 29, an amplifier 30, a tone decoder 32A for detection; of the modulation signal, which via the winding 34A causes the relay 36A to give an indication of said modulation, when it is picked up by the road marker because a vehicle is near it. This is because the slbyfs 10 and 20 then constitute a fringe former, admittedly with a low degree of effectiveness, all the while its core will always be, at least partially, nothing but air.

Når bryter 24 lukkes, vil kondensator 22 bli kortsluttet, men kjbretbyslbyfen 20 vil oppfange litt enérgi fra en nærliggende veibaneslbyf© 10 med frekvens f^, og der vil sirkulere en svak strbm gjennom slbyfe 20 og bryter 24. Induktansen i slbyfe 20 When switch 24 is closed, capacitor 22 will be short-circuited, but kjbretbyslbyfen 20 will capture some energy from a nearby roadway slbyf© 10 with frequency f^, and there will circulate a weak strbm through slbyfe 20 and switch 24. The inductance in slbyfe 20

vil gi en reflektert impedans i slbyfe 10, hvilket vil fore -will give a reflected impedance in slbyfe 10, which will cause -

til at avstemningen av slbyfe 10 i veibanen vil endre seg og frembringe en faseforandring og . en liten forandring i signalets amplityde. Disse forandringer kan gå den ene eller andre vei, to the fact that the tuning of slbyfe 10 in the roadway will change and produce a phase change and . a small change in the amplitude of the signal. These changes can go one way or the other,

alt avljengig av hvordan veibaneslbyf en er avstemt og hvilken reflektert impedans som forekommer. all depending on how the roadway slbyf is tuned and what reflected impedance occurs.

Når bryter 24 er åpen vil kjbretbyets slbyfe 20 og kondensator 22 danne en resonanskrets som kan svinge med frekvens f^. Når kjbretbyet passerer slbyfe 10 vil et ganske sterkt signal opptre over slbyfe 20 og strbm sirkulere i kretsen, som igjen gir seg utslag i en reflektert impedans i veibaneslbyfen 10, og produserer en modifikasjon av det opprinnelige signal. Hvis bryter 24 lukkes og åpnes med frekvens f^, vil signalet i veibaneslbyfen også inneholde denne modulasjonsfrekvensen f2/sållenge som kjbretbyet er i nærheten av veibaneslbyfen. Ved åpen bryter 24 vil de reaktive komponentenenav impedansen i resonanskretsen kansellere hverandre, hvilket levner bare slbyfemotstanden i 20, i parallell med tapsmotstanden, samt viklingskapasiteten: .i slbyfe 20, reflektert inn i veibaneslbyfen 10, som selv har en liknende lav impedans, modifisert med viklingsforholdet og en kompleks koplingskoeffisient. "Q"-faktoren i veibaneslbyfen blir betydelig forandret og en markert forandring i signalnivået i veibaneslbyfen 10 fremkommer som et resultat av dette. When switch 24 is open, the circuit breaker 20 and capacitor 22 will form a resonant circuit which can oscillate with frequency f^. When the kjbretby passes the slbyfe 10, a fairly strong signal will appear over the slbyfe 20 and strongly circulate in the circuit, which in turn results in a reflected impedance in the roadway slbyfe 10, and produces a modification of the original signal. If switch 24 is closed and opened with frequency f^, the signal in the roadway slbyfen will also contain this modulation frequency f2/as long as the kjbretby is in the vicinity of the roadway slbyfen. When switch 24 is open, the reactive components of the impedance in the resonant circuit will cancel each other, leaving only the slbyfe resistance in 20, in parallel with the loss resistance, as well as the winding capacity: .i slbyfe 20, reflected into the roadway slbyfe 10, which itself has a similarly low impedance, modified the turns ratio and a complex coupling coefficient. The "Q" factor of the roadway signal is significantly changed and a marked change in the signal level of the roadway signal 10 occurs as a result of this.

Signalet i veibaneslbyfen 10 sendes så gjennom transformator 14 til demodulator 28, og et forsterket signal opptrer i tonedekoder 32A. Hvis signalet ved frekvens f^i det aktuelle tilfelle er modulert med frekvens f 2, så vil tonedekoderen sende et signal til utgangskretsen 36A, som så vil vise at det kjoretoy som skal identifiseres virkelig er i nærheten av veibaneslbyfen 10. The signal in the roadway signal 10 is then sent through transformer 14 to demodulator 28, and an amplified signal appears in tone decoder 32A. If the signal at frequency f^ in the relevant case is modulated with frequency f 2, then the tone decoder will send a signal to the output circuit 36A, which will then show that the vehicle to be identified is really in the vicinity of the road marker 10.

Fig. 2 viser tidsforlbpet av det signal som mottas av identifiseringskrets 26 mens kjbretbyet passerer over veibaneslbyfen. Signalet oker i styrke når kjbretbyer nærmer seg veibaneslbyfen, faller til nulllnår kjbretbyets slbyfe krysser kanten på veibaneslbyfen, Fig. 2 shows the time course of the signal received by the identification circuit 26 while the road bridge passes over the road section. The signal increases in strength when the kibretbye approaches the roadway slbyfe, falls to zero when the kibretbye slbyfe crosses the edge of the roadway slbyfe,

og når et maksimum når kjbretbyets slbyfe ligger over og innenfor veibaneslbyfen. Fasongen på kurven avhenger av forholdet mellom slbyfenes stbrrelser, idet fig. 2 angir et tilfelle hvor kjbretbyets slbyfe er forholdsvis liten. and reaches a maximum when the kjbretbyen slbyfe lies above and within the roadway slbyfe. The shape of the curve depends on the relationship between the slbyfen's stbrrls, since fig. 2 indicates a case where the kjbretbyen's slbyfe is relatively small.

Fig. 1 viser også en annen tonedekoder 32B, rele 34B og anviser 36B. Dette system anvendes når der er mer enn ett kjoretoy eller en klasse kjoretoy som skal detekteres. Hver klasse kjoretoy har da sin spesielle modulasjonsfrekvens f^, og tilsvarende tonedekoder detekterer denne frekvens og gir signal til den tilhbrende anviser. Skjbnt der er vist bare to tonedekodere osv., Fig. 1 also shows another tone decoder 32B, relay 34B and indicator 36B. This system is used when there is more than one vehicle or one class of vehicle to be detected. Each class of vehicle then has its own special modulation frequency f^, and corresponding tone decoders detect this frequency and give a signal to the appropriate operator. Unfortunately, only two tone decoders, etc., are shown there.

så kan der i praksis anvendes mange flere, fra 15 og opp til 50, bestemt av kretsen og komponenter, og om man skal detektere et stbrre antall kjbretbyer eller klasser av kjbretbyer. Alternativt kan den tilgjengelige modulasjonsbåndbredde anvendes til transmisjon av små mengder data, i tillegg til simpel identifisering. then in practice many more can be used, from 15 up to 50, determined by the circuit and components, and whether a greater number of cybernetic cities or classes of cybernetic cities are to be detected. Alternatively, the available modulation bandwidth can be used for the transmission of small amounts of data, in addition to simple identification.

Maksimum modulasjonsfrekvens er bestemt av stigetiden for oscillasjonen i resonanskretsen, og er typisk 3 kHz, med ovre bærefrekvens i området 50 tii 150 kHz. The maximum modulation frequency is determined by the rise time of the oscillation in the resonant circuit, and is typically 3 kHz, with an upper carrier frequency in the range 50 to 150 kHz.

Fig. 3 viser et eksempel på utfbreisen av den apparatur som er angitt i ramme 18 på fig. 1. En konvensjonell firkantbblge-oscillator 36 produserer en stabil firkantbblge med den angitte modulasjonsfrekvens f2/på en slik måte at forholdet mellom signal og mellomrom gir maksimum rms-signal i veibaneslbyfen for å kompensere for stigetiden i kjbretbyslbyfen. Dette signal tilfores porten på en felteffekt-transistor (FET) 38, f.eks. type 2N 4860A, eller en annen passende type faststoff-bryter, som veksler mellom full ledning og ikke-ledning. Kjoretoyslbyfen 20 og kondensator 22 er koplet over transistor 38/ som da utgjor den bryter 24 som er angitt på fig. 1. Kretsen tilfores 9 volt likespenning fra kjbretbyets batteri via en spenningsregulator, eller fra et eget batteri. Fig. 3 shows an example of the output of the apparatus indicated in frame 18 of Fig. 1. A conventional square wave oscillator 36 produces a stable square wave with the specified modulation frequency f2/ in such a way that the signal-to-space ratio provides the maximum rms signal in the roadway signal to compensate for the rise time in the bridge signal. This signal is applied to the gate of a field effect transistor (FET) 38, e.g. type 2N 4860A, or other suitable type of solid state switch, which toggles between full conduction and non-conduction. Kjoretoyslbyfen 20 and capacitor 22 are connected via transistor 38/ which then forms the switch 24 which is indicated in fig. 1. The circuit is supplied with 9 volts DC from the kjbretby's battery via a voltage regulator, or from a separate battery.

Oscillatoren 36 (fig. 3) er koplet til en av to frekvensbestemmende motstander, 42A og 42B, via brytere 4lA og 4lB, som kan f.eks. The oscillator 36 (fig. 3) is connected to one of two frequency-determining resistors, 42A and 42B, via switches 41A and 41B, which can e.g.

være reed-releer. Når en av bryterne lukkes, vil tilsvarende motstand sbrge for at oscillator 36 vil tilfore en viss frekvens f2til porten på transistor 38. be reed relays. When one of the switches is closed, the corresponding resistance will ensure that oscillator 36 will supply a certain frequency f2 to the gate of transistor 38.

I praksis må kjbretbyets slbyfe avstemmes etter at den er tilpasset og montert på undersiden av kjbretbyet, fordiimetallet i chassiset vil forandre induktansen i kretsen. Dessuten kan slbyfen skjermes, på den siden som vender mot chassiset, ved hjelp av en metallplate, f.eks. aluminium, for å minimalisere kjbretbyets effekt på kretsens avstemning. Kjbretbyets slbyfe kan forbvrig erstattes med en ferritt-antenne, nemlig et antall trådviklinger i nært elektro-magnetisk samspill med en ferrittstang. In practice, the circuit board's slbyfe must be tuned after it has been adapted and mounted on the underside of the circuit board, because the metal in the chassis will change the inductance in the circuit. In addition, the slbyf can be shielded, on the side facing the chassis, by means of a metal plate, e.g. aluminium, to minimize the effect of the city on the constituency's vote. Kjbretbyet's slbyfe can be temporarily replaced with a ferrite antenna, namely a number of wire windings in close electro-magnetic interaction with a ferrite rod.

I dette system for identifisering av kjbretbyer i henhold til oppfinnelsen vil maksimum signal fremkomme hvis veibaneslbyfen har en eneste torn og kjbretbyets slbyfe har et stor antall torn, altså maksimum forskjell. Men "Q"-faktor i veibaneslbyfen vil bli liten med bare en torn, og motstanden i kjbretbyets slbyfe vil bli stbrre når der er mange torn. Det er derfor nbdvendig med et kompromiss, med to eller tre torn i veibanen og 15-25 på kjbretbyet. In this system for identifying bridge towns according to the invention, the maximum signal will appear if the roadway slbyfe has a single spike and the bridge town's slbyfe has a large number of spikes, i.e. maximum difference. But the "Q" factor in the roadway slbyfe will be small with only one thorn, and the resistance in the highway slbyfe will be greater when there are many thornes. A compromise is therefore necessary, with two or three towers in the roadway and 15-25 in the kjbretbyet.

En modifisert apparatur kan anvendes i forbindelse med konvensjonelle fastfrekvens kjbretbydetektorer, idet der utfores visse forandringer. F.eks., slbyfen i veibanen må avstemmes like under eller like over resonans ved den fbrste frekvens f^, idet differansen kan være opptil 5 %. Kretsen er vist på fig. 4, som er maken til fig. 1 unntatt at en f asediskriminator 46 og et- utgangstrinn 48 er koplet til transformator 14. Når et kjoretoy uten omtalte slbyfe nærmer seg veibaneslbyfen 10, vil metallet i kjbretbyet forårsake en forandring i "Q."-faktor i sistnevnte slbyfe, og gi en faseforandring som detekteres av fasediskriminator 46, og et signal tilfores utgangskretsen 48. Ennvidere, hvis en inngang på en MAVTS krets plassert ved veibanen tilfores signal gjennom en skilletransformator, så;r.kan demodulator i MAVTS koples over slbyfen i en konvensjonell fast-frekvens kjoretoydetektor. Disse modi-fikasjoner gir en enkel veibaneslbyfe en dobbel funksjon. A modified apparatus can be used in connection with conventional fixed frequency kibretby detectors, as certain changes are made. For example, the slbyfen in the roadway must be tuned just below or just above resonance at the first frequency f^, the difference can be up to 5%. The circuit is shown in fig. 4, which is similar to fig. 1, except that a phase discriminator 46 and an output stage 48 are connected to the transformer 14. When a vehicle without said slbyfe approaches the roadway slbyfe 10, the metal in the kjbretby will cause a change in the "Q." factor in the latter slbyfe, giving a phase change which is detected by phase discriminator 46, and a signal is applied to the output circuit 48. Furthermore, if an input of a MAVTS circuit located at the roadway is applied to the signal through an isolation transformer, then the demodulator in the MAVTS can be coupled across the slbyf in a conventional fixed-frequency vehicle detector . These modifications give a simple roadway slbyfe a double function.

Fordelen med foreliggende oppfinnelse over eksisterende utstyr er at det mottatte bærefrekvenssignal er kraftig, opptil 6 volt rms eller mere, hvilket gir bedre signal/stby forhold, og dette forhold blir ytterlrere forbedret ved det båndpassfilter som er avstemt til bærefrekvensen, idet filteret fjerner interfererende AM-signaler, f.eks. fra langbblge kringkasting, og fjerner dessuten lavfrekvent induksjon fra nedgravde kabler som kan ligge.-'på en av modulasjonsfrekvensene. Videre er der ingen transmisjon av energi fra annet utstyr på kjbretbyet, hvilket fjerner de problemer som måtte oppstå ved at mobile sendere interfererer med annen apparatur, og endelig er utformingen av veibaneslbyfen sleikt ikke kritisk på noen måte. The advantage of the present invention over existing equipment is that the received carrier frequency signal is powerful, up to 6 volts rms or more, which gives a better signal/noise ratio, and this ratio is further improved by the bandpass filter which is tuned to the carrier frequency, as the filter removes interfering AM -signals, e.g. from long-haul broadcasting, and also removes low-frequency induction from buried cables which may lie.-'on one of the modulation frequencies. Furthermore, there is no transmission of energy from other equipment on the networked city, which removes any problems that may arise from mobile transmitters interfering with other equipment, and finally, the design of the road network is not critical in any way.

Claims

1. A vehicle, characterized in that it is equipped with a . isolated multi-burner electric slbyfe (20) which constitutes a transformer together with an electric slbyfe -(10) in the roadway when said slbyfe (10, 20) are close to each other, a device (22) for tuning the kjbretby's slbyfe (20), and which together with this form a bridge circuit which has resonance at a first frequency, as well as a device (24) for modulating said bridge circuit with another frequency, so that in operation, a signal modulated with said second frequency can be induced from the bridge bridge's slbyfe (20 ) to a nearby mentioned slbyfe (10) in the roadway for identification of said vehicle.

2. A vehicle as set forth in claim 1, characterized in that said device (24) for modulation is constructed so that it periodically short-circuits all or parts of said electrical circuit.

3. A vehicle as set forth in claim 2, characterized in that all or parts of said electrical circuit are periodically short-circuited by a solid-state switch (24).

4. A vehicle as specified in any of the preceding claims, characterized in that said first frequency is in the range from approx. 50 kHz to approx. 1.50 kHz.

5. A vehicle as specified in any of the preceding claims, characterized by said second frequency being in the range from approx. 300 Hz to approx. 3000 Hz.

6. A vehicle as stated in any one of the preceding claims, characterized in that said slbyfe (20) mounted on the kjbretbye consists of a number of wire windings.

7. A vehicle as specified in claim 6, characterized in that the number of windings-in the slbyfen (20) in the kjbretbyet lies in the area from-oa . 15 to approx. 25.

8. A vehicle as stated in claim 6 or 7, ki.a characterized in that the slbyfen (20) on the kjbretby is flat and is mounted so that its plane is essentially parallel to any roadway that the kjbretby uses.

9. A vehicle as stated in claim 8, characterized in that the slbyfen (20) on the kjbretbyet is era. 300 mm square.

10. A vehicle as stated in any one of claims 1 to 5, characterized in that said slbyfe (20) on the kjbretbyet is a ferrite antenna.

11. A vehicle as stated in any one of the preceding claims, characterized in that said slbyfe (20) on the kjbretby is shielded on the side facing the chassis of the kjbretby.

12. A device for identification of road cities, characterized in that it comprises a slbyfe (10) on or in the upper layer of the roadway, a device (12) for tuning the roadway slbyfe (10), a device (16, 17) for supplying energy to the roadway slbyfe (10) at a first frequency which is at least close to the resonant frequency of the tuned slbyfe (10), as well as a circuit (26) for identifying vehicles which comprises a device for demodulation (28) and a device for frequency detection ( 32) arranged for detection in the roadway marker (10) of any signal at said first frequency and modulated with another frequency, the said second frequency being produced to thereby identify a vehicle according to claim 1, and said first frequency being common to the road marker ( 10) and slbyfen (20) at kjbretbyet.

13. A device for identification as stated in claim 12, characterized in that said first frequency lies within the range from approx. 50 kHz to approx. 150 kHz.

14. A device for identification as specified in claim 12 or in 3, characterized in that the road marker (10) has a number of thorns from 1 to 3.

15. A device for identification as set forth in any of claims 12 to 14, characterized in that said device for frequency detection (32) has a number of tone decoders whereby signals modulated with different values of said second frequency can be detected separately and thereby different classes of kjbretbys can be identified.

16. A device for identification as set forth in any of claims 12 to 15, characterized in that said resonance frequency for the tuned roadway slbyfe (10) deviates from said first frequency up to approx. 5%.

17. A device for identification as set forth in any of claims 12 to 16, characterized in that a device for phase discrimination (46) is connected to the roadway indicator (10) and is arranged so that it provides an output signal by which a vehicle which is not equipped with said indicator (20) can be detected, the said device for phase discrimination ( 46) when said kjbrétby is in the vicinity of the roadway slbyfen (10) will detect a phase change in a signal at said first frequency in the roadway slbyfen (10).

18. A system for identifying a vehicle, i characterized in that it comprises a roadway slbyf e (10) on or in a roadway, a device (12) for tuning the roadway slbyf (10), and a device (16, 17) for supplying energy to the roadway slbyf (10) by a first frequency at least close to the resonant frequency of the tuned roadway slbyfe (10); further that it comprises, on at least one vehicle that must be identified when it uses said roadway which has a roadway slbyfe (10), an insulated multi-burner kjbretbyslbyfe (20) mounted on the kjbretby so that it forms a transformer together with said roadway slbyfe when said two slbyfe are in the vicinity of each other, a device (22) for tuning said slbyphereslbyfe (20) for designing a slbyphereson circuit on the slbypheresby which has resonance essentially at said first frequency, a device (24) for modulating said slbyphereson circuit with a different frequency; as well as an identification circuit (26) for vehicles comprising a demodulation device (28) and a detection device (32) for frequency arranged to detect in the roadway signal (10) any signal at said first frequency which is modulated with said second frequency.

19. - A system as stated in claim 18, characterized in that said detection device (32) for frequency has a number of tone detectors whereby signals modulated with different values for the second frequency can be detected separately, so that different classes of vehicles can be identified.

20. A system as stated in claim 18 or 19, characterized in that the resonance frequency for said roadway block (10) deviates from said first frequency by up to 5%.

21. A system as set forth in any one of claims 18 to 20, characterized in that a device (46) for phase discrimination is connected to the roadway slbyfe (10) and is arranged so that it provides an output signal whereby a vehicle that is not equipped with a slbyfe can be detected by a phase change in a signal at the first frequency in the road lane signal (10) when said vehicle is nearby.